What is the health status of the songbirds on the Galápagos Islands?
The landbirds of the Galápagos Islands are of particular concern to us, because unfortunately the last counts of Birgit Fessl and her team have confirmed the assessment of the World Conservation Union (IUCN), that currently half of all landbird species of the archipelago are threatened. After Floreana Island, the island of Santa Cruz has recorded the most severe population declines.
As often happens, man is the cause of these problems. Introduced plants and agricultural use are altering the birds' habitat, and invasive species such as the bird vampire fly (Philornis downsi) threaten the survival of bird chicks. Additionally, avian pathogens also enter the archipelago through introduced poultry or migratory birds. These pathogens spread to native and often endemic Galápagos birds, posing a further threat to already dwindling songbird populations.
Threats from infectious diseases
Recent findings indicate that emerging infectious diseases pose a major risk to small animal populations living on remote islands such as Galápagos, because they have not been able to develop defense mechanisms against the pathogens, which can then lead to a drastic reduction in animal populations.
As early as 2008, both poultry and wild birds on the inhabited islands of Floreana, San Cristóbal and Santa Cruz underwent health checks. Antibodies to various parasites and pathogens were found in some of the birds, suggesting that these animals had undergone infection. Unfortunately, at that time, there was a failure to establish long-term health monitoring of the birds or to seek more advanced studies.
However, this would have been important because some of the pathogens detected at that time may be detrimental to the survival of the endemic birds of the Galápagos Islands. Furthermore, they pose a risk to public health because some of them lead to zoonosis, which means that avian disease can also pass to humans. Therefore, it is important to determine which pathogens are already present in the Galápagos and the extent to which they have spread. This information can then be used to develop effective protective strategies to address existing diseases and reduce the risk of new pathogens being introduced by humans.
Mockingbird infected with bird poxã Paquita Hoeck
Therefore, in 2019, on the islands of Santa Cruz and Floreana, samples of various Darwin's finch species, mockingbirds and other songbirds were started to be analyzed for possible pathogens.
Biologist Birgit Fessl and her team managed to conduct health checks and tests for avian diseases on more than 400 wild birds and chickens, taking swabs from each bird's throat, beak and the cloaca. These samples are now undergoing molecular biology testing at the Charles Darwin Station (CDF) laboratory under the direction of veterinarian Dr. Ainoa Nieto-Claudin, who also led the giant tortoise health analysis project. Positive samples are sorted out for further genetic analysis. The studies will focus on the following six infectious diseases that could pose a threat to the land birds:
Avian adenovirus and Newcastle disease have both been previously identified in poultry and land birds. Newcastle virus is also known to affect humans. In addition, mycoplasmosis and Marek's disease, a herpes virus that preferentially affects chickens and thus also poses transmission risks to humans. Avian influenza has not yet been detected in the Galápagos; but since it is widespread in Ecuador, the risk of its transmission by migratory birds is considered to be very high. In addition, associated with antibiotic resistance, Salmonella disease has been detected on poultry farms on Santa Cruz Island, which may pose a public health threat.
Healty Vermilion Flycatcher ã David Anchudia
Future protection is important
The comparison of the information obtained with the data from 2008 is the basis for developing much-needed basic protection strategies for the birds.
We reported in the last edition of Galápagos Intern that currently on Floreana Island, large numbers of the land bird population are living in quarantine enclosures as bait is placed throughout the island to eradicate invasive domestic rats (Rattus rattus).
For this project, the testing done by Birgit and Ainona's teams is very important as it will help ensure that the birds will have the best possible health conditions when they are released from quarantine and reintroduced to the island, which is planned for late 2023/early 2024.
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